Sparking plug



Apr. m, w23. www? E, PETHOUD SPARKING PLUG Filed Sept. 30, 1920 @MKM/@ CII Patented Apr. l0, 1.923.

UNITED STATES EDOUARD PETHOUD, OF LAUSANNE, SWITZERLAND.

SPARKING PLUG.

Application filed September 30, 1920.

To all whom it may concern.'

Be it known that I, EDOUARD PETHOUD, citizen of Republic of Switzerland, residing` at Lausanne, Switzerland, have invented certain new and useful Improvements in Sparking Plugs, of which the following is a specification, reference being made therein to the accompanying drawing.

The present invention relates to sparking plugs for internal combustion engines of that type which comprises a. chamber of which the inner end or bottom is formed by the insulator and of which the other walls are formed by an outer grounded electrode, and along which chamber the central electrodeextends.

The present invention has for its object to provide an improved sparking plug of the typereferred to which comprises means designed to protect the said inner end of the insulator or bottom of the chamber from all direct contact with foreign bodies (such as drops of oil, explosion gases, etc).

The main features of the present invention are the following The said chamber is divided into two compartments by a diaphragm having a central aperture .through which the central electrode extends.

This central electrode carries near its outer end a disc having a diameter at least equal to thediameter of the central hole 'in the said diaphragm.

This disc has preferably a convex surface which faces the outer end of the central electrode.

The diaphragm may be provided with a central sleeve-shaped extension surrounding the central electrode and facing towards the outer end of the latter. i

The two last mentioned features, namely the outwardly convex disc and the central sleeve-like extension of the diaphragm, may be combined together in one and the same sparking plug.

The walls of the Vouter chamber compartment (that which is nearest the outer end of the central electrode) have at least one aperture at a level very near the level of the diaphragm which constitutes the end of the said compartment. As an additional security a third, baifle may be secured to the central electrode.

A constructional` form of yan improved Serial No. 413,771.

sparking plug according` to this invention is illustrated by way of example in the ac companying drawings in which Fig. l is an elevation.

F ig. 2 wis an axial section, and

Fig. 3 is a plan of the improved sparking ilufg. l Als shown, the central electrode a of the plug is arranged in the axial bore of the insulator o which is fixed in a socket c of metal, for instance of mild steel. d and di are the usual washers placed, respectively, between the socket c and the insulator b, and between the latter and the central electrode a. e is a washer of soft metal for instance aluminum, which serves to fix the insulator in the socket.

The central electrode a bears against the insulator by means of a shoulder al which is pressed` against the asbestos washer all by means of a thumb nut f bearing against the other end of the insulator Upon the screw-threaded portion of the central electrode there is further screwed a. second nut f1, between which and the nut f a conductor (not shown) connected to one of the terminals of a supply of electricity may be clamped.

On the outer end of the screwthreaded part of the socket c there is xed a cap h of internally ogival form which constitutes the peripheral (outer) electrode, the socket c being connected through the frame of the engine tothe other terminal of the supply of electricity. f i

The sparks occur between the free (outer) end of the central electrode a and the edge or edges of an aperture h1 which preferably has the shape of a threefpointed star formed in the top of the cap L.

The central electrode thus extends through a chamber the inner end or bottom of which is constituted by the insulator b Vand the outer walls of which are constituted partly by the sides of the screwthreaded part of the socket c and partly by the cap-shaped peripheral (outer) electrode L. This chamber is divided into inner and outer compartments by a transverse diaphragm g which has a central aperture g1 for the passage of the central electrode.f `This diaphragm constitutes or closes the inner end of the cap electrode t.

The central aperture g3 is preferably formed b v a central sleeve or extension g* its outensurface, that is to say, its surface facing the sparking gap between the free (outer) ends of the two electrodes c and 7L.

The outer electrode /i has at its base one or more holes 7b2 opening into the outer chamber in front of and as close as possible to the plane of the transverse diaphragm g.

The relative arrangement of these holes diaphragm g and convex disc (/1 is such as to cause a current of air to flow from i the central aperture lil towards the holes lig,

which will carry all foreign bodies (dust, drops of oil, explosion gases) to the hole or holes k2. These foreign bodies which would otherwise pass intothe interior 'of the plug and thus clog the inner end of the insulator orbottom of the chamber lsurrounding the central electrode, will thus find a ready escape through the hole or holes h2. In addition to this advantage the presence of the baffle g constricts the area of the annular passage between itself and the outer electrode 7L, increasing the velocity ofgas past its edge and creating an expansion of gas in theiinsulator chamber the entrance to which is immediately above the baffle g and adjacent the restricted portion of said gas passage. This expansion is created by the ejector action of the rapidly moving gases flowing between the baille and the outer wall of the cap, thus minimizing the extent of the tidal rise of the exploded gas into said insulator chamber.

If desired, the outwardly convex disc g1 may have a concave inner surface facing the central `-aperture g3. l

'VThe disc g1, as well as the sleeve g'i may however have any other shapes that will serve to guide the current of air and the foreign bodies entering at h1 towards the hole orholes h2. For instance the disc g1 may be replaced by a part having the shape of a chimney cowl and fixed upon the aperturedv diaphragm g or upon the sleeve g4. As an additional security a third baffle g2 may be secured to the central electrode.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is l. A spark plug comprising a shell, an insulator within said shell and terminating short of the inner end thereof, a central elec- Lesage? trode carried by said insulator projecting from said shell, a cap secured to the end of said shell having an aperture surrounding the central electrode and forming a spark gap therewith and provided with a lateral aperture above said spark gap cooperating with the latter to form a draft passage within said cap, and al baffle within said cap arranged in a plane intermediate said apertures to deflect the draft from said insulator.

2. spark plug comprising a shell, an insulator within said shell, a central electrode carried by said insulator and projecting beyond the shell, a cap secured to the end of said shell and siu'rminding the central electrode, said cap comprising walls united at their top and elsewhere spaced apart, each of said walls proj ecting out-wardly forming an` annular gas chamber in theV upper part of said cap, said outer wall having a central aperture forming a spark gap with said cent-ral electrode and said inner wall being provided with an aperture of larger diameter than said sparkgap` said outer wall having a lateral aperture in the zone of said annular gas chamber.

3. A spark plug comprising a shell, an insulator within said shell, a central electrode carried by said insulator and projecting beyond the shell, a cap secured to the end of said shell and surrounding the cent-ral electrode, said cap comprising walls united attheir top and elsewhere spaced apart, each of said walls projecting outwardly forming an annular gas chamber therebetween, the outer wall having a central aperture forming a spark gap with the central electrode, and the inner wall being provided with an aperture of larger diameter than said spark gap, a baille associated with said central electrode and located between said apertures, said outer wall having a lateral aperture in the Zone of said annular gas chamber.

4f. A spark plug comprising a shell, an insulator within said shell, forming with the walls of said shell an insulator chamber, a central electrode carried by said insulator and project-ing beyond the shell, a cap secured to the end of the shell and surrounding the central electrode, said cap comprising walls united at their top and elsewhere spaced apart, the outer wall having a central aperture forming a spark gap with said central electrode and the inner wall projecting outwardly from said shell to form a sleeve communicating' with said insulator chamber and terminating within said outer wall at a point intermediate its upper and lower ends forming an annular gas chamber in the upper part of said cap, said outer wall having' a lateral aperture in the zone of said gas chamber to provide a gas passage through said cap for gas entering at the spark gap, a baffle associated with the central electrode and lying between the spark gap and the sleeve portion of the inner wall, said baille cooperating with said sleeve portion to form an entrance to the insulator' chamber above said baille and cooperating with the outer wall to form a restricted section of said gas passage, said baille function ing by increasing the velocity of gas past its edge to creat-e an expansion of gas in the insulator chamber and counteract t-he pressure of the explosion within said insulator chamber.

A spark plug comprising a shell, an insulator within said shell7 a central electrode carried by said insulator and projecting beyond the shell, a cap secured to t-he end of said shell and surrounding the central electrode7 said cap comprising` an inner member having an outwardly nrojecting central sleeve and an outer mem er of ogival form surrounding the sleeve portion of said inner member and contacting with the outer peripheral edge thereof, said inner and outer member forming an annular gas chamber, said outer member having an aperture at its Central portion forming with the central electrode a spark gap and having a lateral aperture in the zone of said annular gas chamber, and a baille associated with the central electrode and located between the spark gap and the sleeve portion of the inner member.

In testimony whereol I have signed my name to this specii'ication in the presence ol' two subscribing witnesses.

EDOUARD PETHOUD,

Witnesses H. MANUEL, D. CLETMEST. 

